This invention relates to corner posts used in the packaging of articles and, more particularly, to corner posts applied, for example, as vertical corner posts such as for application to the corners of a straight-sided article or container adapted for cushioning the straight corners and edges of packaged articles along the full height thereof and also adapted to permit the stacking of the packaged articles on each other without damaging the container or the article, and horizontal corner posts permitting pick up and movement of packaged articles by a squeeze truck without sideways crushing of the articles.
In packaging a number of articles including heavy articles such as refrigerators, television sets, stoves, air conditioners, and washing machines and dryers, it is customary to package them in relatively lightweight containers formed of paperboard or corrugated. The article is located and cushioned within the container by corner posts which typically are one or more pieces of cardboard folded to a 90.degree. angle and inserted along the edges of the articles and the corners of the container. Such corner posts are used to provide cushioning to protect the corners of the packed article from damage such as scratching and denting during shipping and handling. A series of relatively narrow straps are typically wrapped around the container to secure the container and corner posts. These straps which may be a metal such as steel or a high strength plastic are tensioned to secure the package and absent corner posts would bite into the edges of the corrugated packaging and the article contained therein. Further, it is customary to package articles by enveloping them in a plastic film such as by shrink or stretch wrap techniques. Again, the edges of the article are cushioned and protected by corner posts extending along the length thereof secured inside the plastic film.
A number of corner posts are known to the art. Representative of such designs are U.S. Pat. Nos. 2,068,771; 2,160,221; 2,196,157; 2,514,833; 3,556,529; 3,133,687; 3,337,111; 3,536,245; 3,072,313; 3,433,354; 3,708,101; 3,734,389; 4,120,441; and G.B. 2,080,767. These prior art corner posts, however, all have one or more of the following disadvantages. Although some provide relatively good cushioning, they do not provide a load bearing capacity in the vertical direction which would permit the vertical stacking of loaded containers or, if they do, they are of substantial bulk and thus require large amounts of materials, are heavy, and take up space. For protectors not providing vertical load bearing capacity, when stacking of such containers is attempted, the weight of the upper container crushes the underlying containers by bending or buckling the walls of the container which bear the stacking load. Others which attempt to provide such vertical load bearing capacity in turn do not always provide sufficient cushioning and/or are relatively complex in design and expensive to manufacture. Since the packaging materials do not add value to the product itself, the cost of such materials are an important consideration to the manufacturer who uses such posts in shipping finished goods. Finally, some designs are subject to crushing by lateral forces supplied to the container and by shifting movement of the articles within the container detracting from the cushioning protection for the edges and corners of the article.
In my U.S. Pat. No. 4,771,893, I provide an integral, elongated corner post for cushioning and protecting the edges of a packaged article which provides excellent vertical load bearing or stacking strength and excellent horizontal load bearing strength as the case may be, good cushioning, good impact resistance, substantial thickness for spacing the outer surface of the packaged article from the side walls of the container or film but with a minimum of material, and which is lightweight, clean with no rough edges and simple in design and relatively economical to produce.
In my U.S. Pat. No. 4,865,201, I provide a combination laminated corrugated paper corner post which has improved shock resistance, increased columnar and beam strength, and a better ratio of strength to unit weight.
Also known to the art is a corner posts comprised of multiple layers of elongated paperboard which are laminated together, glued, treated, and formed into rigid right angles. The thickness of the corner post is determined by the number of layers of paperboard laminated together and typically ranges from 0.120 inch to approximately 0.400 inch. It is further known to place spaced dots of a special adhesive which allows the user to stick the corner post in place. The corner post thus grips the corners of the load until the stretch wrap or strap is applied. In this application, however, because the corner posts are shipped in stacks to conserve space, it is necessary that a release paper cover the adhesive faces of the corner posts to prevent the sticking together of adjacent corner posts in a stack.